Atom-probe tomography (APT) and first-principles calculations are employed to investigate the partitioning of Mo in the γ(f.c.c.)-and γ′(L1 2)-phases in a model Ni-6.5Al-9.9Mo at. superalloy. Mo is experimentally observed to partition preferentially to the γ(f.c.c.)-matrix, which is consistent with the smaller value of the γ(f.c.c.)-matrix substitutional formation-energy, with a driving force of 0.707 eV for partitioning as determined by first-principles calculations. APT measurements of the γ′(L1 2)-precipitate-phase composition and Al-, Mo-centered partial radial distribution functions indicate that Mo occupies the Al sublattice sites of the Ni 3Al(L1 2) phase. The preferential site-substitution of Mo at Al sublattice sites is confirmed by first-principles calculations.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)